Beef being the older animal is naturally more flavoursome and, in my opinion, there is more value in the cut. Not only is it cheaper per kg but it has a higher meat to bone ratio than its veal counterpart.
This is what you have to weigh up the decision making against (whether to cook with beef or veal osso bucco):
With regard to bones, being a younger animal than beef, veal bones have more cartilage than beef bones. As the animal ages, cartilage converts to bone. As a cook, it is important to know that cartilage in the bones converts to gelatine during long and slow cooking. It is for this reason that, sometimes, I will slow cook veal osso bucco rather than beef.
Slow cooking with the bone still in causes the bones to release gelatine. This enhances flavour, provides moisture and gives texture and “stickiness” to both the meat and the sauce. This is particularly important with veal as its natural flavour is less pronounced than the older beef.
To put it another way, beef has more flavour because it comes from an older and more exercised animal. However veal has more gelatine content which enriches meat dishes – the meat is ‘stickier’.
So both the older beef and the younger veal have their culinary advantages. The above is what I advise you to consider when deciding on beef or veal osso bucco for your next braised dish.